Formwork lock having two parallel locking slots



Nov. 3, 1964 s. E. ANDERSSON 3,154,998

FORMWORKLOCK HAVING TWO PARALLEL LOCKING SLOTS Filed March 28, 1962 United States Patent 3,154,998 FSRMWQRK LUCK HAVHQG TWG PLLEL LQCKING SLQTS Sven Elof Andersson, Lidabergsgatan 38, Nari-hoping, weden Filed Mar. 28, 1962, Ser. No. 183,290 4 Claims. (Cl. 8536) Formwork for casting concrete often consists of two boards of wood or other suitable material which are held the required distance apart by means of transverse formwork stays. 'Ihese formwork stays extend beyond the walls of the formwork, which are fastened to the stays by special formwork locks. A formwork lock of this type may consist of a fiat rectangular plate with its shorter ends bent upwards and having a central wedge-shaped slot extending lengthwise and having bevelled edges, the maximum width of the slot being greater than the thickness of the formwork stay. When required to be used, the lock is threaded on to a formwork stay with its fiat side against the wall of the forrnwork, whereupon it is fixed to the formwork stay by blows from the wedge-shaped shorter side, the bevelled edge of the slot being forced into the stay.

The present invention relates to an improved formwork lock of the kind described, this improvement consisting in that it is self-locking when a tractive load is applied. The formwork lock according to the invention consists of a rectangular plate provided with a wedge-shaped longitudinal slot with strai ht edges and of a maximum width which is greater than the width of the formwork stay, and it is characterized by the fact that the plate is bent along the center line of the slot so that the portions of the plate on each side of the slot form in cross-section an obtuse angle with one another, while the edges of the slot in cross-section form an acute angle with one another, in that the plate is likewise bent along a line parallel to the center-line of the slot so that its three arms form in cross-section an isosceles triangle, and in that the arm which forms the base of the triangle is provided with a wedge-shaped slot parallel to the first-mentioned slot and one edge of which, extending inside the upper edge of the slot is bent inwards towards the inside of the triangle, so that when a fo-rmwork stay is fitted into the slots and the formwork lock is struck down over the stay it engages with the latter.

The invention is illustrated in the accompanying drawings, in which:

FIGURE 1 shows a construction of a formwork lock according to the invention, viewed towards the end of a formwork stay,

FIGURE 2 shows the same in cross-section, and

FIGURE 3 shows the same in cross-section when fixed to a formwork stay.

A rectangular plate 1, 2, 3 is provided with a wedgeshaped longitudinal slot 4 having straight edges and having a maximum width which is greater than that of a formwork stay 9. The plate is bent along the center-line of the slot 4, so that the portions 1, 2 of the plate on each side of the slot 4 form in cross-section an obtuse angle with one another and the edges 5 of the slot form in cross section an acute angle with one another.

The plate 1, 2, 3 is also bent along the line parallel to the center-line of the slot 4 so that its three arms 1, 2, 3 form in cross-section an isosceles triangle.

As shown in the drawing, portions 1, 2 of the plate are in elfect upper arms and the portion 3 of the plate is a third arm which underlies the upper arms and forms in cross-section therewith said isosceles triangle. This third arm of plate portion 3 was provided with a further wedgelike slot 6 correspondingly tapered and parallel to the first-mentioned slot 4. The material of the plate in the portion 7 terminates in a edge 7' which as seen in plane in FIG. 1 lies inside the corresponding edge 5 of the firstmentioned slot 4 and is bent inwards towards the inside of the triangle, thus, lying closer to the first-mentioned slot than does the other edge 3' of the portion 8 that defines the slot 6. The arrangement is such that when a formwork stay 9 is fitted into the slots 4, 6 and the formwork lock is struck down over the stay 9, it engages with the latter the bent portion '7 engaging the stay and forcing it against the opposite edges of the slots, thus producing a slight bend in the stay as shown in FIGURE 3.

It has proved advisable to construct the inwardly bent edge of the slot 6 so that it extends as nearly as possible to half the height of the triangle.

It has also been found advisable to shape the other edge of the slot 6 in such a manner that it is slightly bent inwards.

Although only a single embodiment has been de scribed and illustrated, other embodiments are also possible within the framework of the invention.

I claim:

1. A formwork lock for cooperation with a forrnwork stay, said lock comprising a rectangular plate having a tapered, wedge-shaped longitudinal slot therein, said slot having straight edges and a maximum width which is greater than the width of such a stay, said plate being bent along the center line of the slot so that the portions of the plate on each side of the slot form in cross-section two upper arms lying at an obtuse angle with one another, and the edges of the slot in cross-section forming an acute angle with one another, said plate also being bent along a further line parallel to the center line of the slot to form a third arm underlying said upper arms so that said three arms form in said cross-section an isosceles triangle, said third arm constituting the base of said triangle and having therein a further wedge-shaped slo-t correspondingly tapered and parallel to the first-mentioned slot and one edge of said further slot, as seen in plan, lying inside the corresponding edge of the first-mentioned slot and being bent inwards toward the inside of the triangle and lying closer to the first-mentioned slot than the other edge of said further slot.

2. A formwork lock as claimed in claim 1, in which the upwardly bent edge of the said further slot is the edge remote from the said further line.

3. A formwork lock as claimed in claim 1, characterized in that the inwardly bent edge of the slot in the base arm is extended approximately to half the height of the triangle.

4. A formwork lock as claimed in claim 1, characterized in that the other edge of the slot in the base arm is slightly bent inwards.

References Cited in the file of this patent UNITED STATES PATENTS 2,374,107 Joy Nov. 6, 1951 2,798,406 Steck July 9, 1957 2,895,370 Hamann July 21, 1959 3,036,487 Hughes May 29, 1962 

1. A FORMWORK LOCK FOR COOPERATION WITH A FORMWORK STAY, SAID LOCK COMPRISING A RECTANGULAR PLATE HAVING A TAPERED, WEDGE-SHAPED LONGITUDINAL SLOT THEREIN, SAID SLOT HAVING STRAIGHT EDGES AND A MAXIMUM WIDTH WHICH IS GREATER THAN THE WIDTH OF SUCH A STAY, SAID PLATE BEING BENT ALONG THE CENTER LINE OF THE SLOT SO THAT THE PORTIONS OF THE PLATE ON EACH SIDE OF THE SLOT FORM IN CROSS-SECTION TWO UPPER ARMS LYING AT AN OBTUSE ANGLE WITH ONE ANOTHER, AND THE EDGES OF THE SLOT IN CROSS-SECTION FORMING AN ACUTE ANGLE WITH ONE ANOTHER, SAID PLATE ALSO BEING BENT ALONG A FURTHER LINE PARALLEL TO THE CENTER LINE OF THE SLOT TO FORM A THIRD ARM UNDERLYING SAID UPPER ARMS SO THAT SAID THREE ARMS FORM IN SAID CROSS-SECTION AN ISOSCELES TRIANGLE, SAID THIRD ARM CONSTITUTING THE BASE OF SAID TRIANGLE AND HAVING THEREIN A FURTHER WEDGE-SHAPED SLOT CORRESPONDINGLY TAPERED AND PARALLEL TO THE FIRST-MENTIONED SLOT AND ONE EDGE OF SAID FURTHER SLOT, AS SEEN IN PLAN, LYING INSIDE THE CORESPONDING EDGE OF THE FIRST-MENTIONED SLOT AND BEING BENT INWARDS TOWARD THE INSIDE OF THE TRIANGLE AND LYING CLOSER TO THE FIRST-MENTIONED SLOT THAN THE OTHER EDGE OF SAID FURTHER SLOT. 